Home > Companies > PermaRock Products Ltd > PermaRock Exterior Render System (Back-ventilated Render Rainscreen) (Non-Insulated)

External render systems for back ventilated, pressure equalised, rainscreen (wall) applications and for application onto suitable mineral render carrier boards (walls and soffits).

The system includes a range of weather resistant, water repellent decorative through-colour render and brick tile finishes.

Features and benefits:

  • Can be used in buildings over 18 m in height.
  • Mechanical fixings can be introduced to enhance bonding to the underlying substrate and help improve resistance to wind loads.
  • Lightweight, flexible and crack-resistant.
  • Incorporates lightweight reinforcement for additional system durability.
  • Ease of application.
  • Includes a range of decorative finish options.
  • Has a working design life of 30 years.

Please note that this is a non-insulated system; consult manufacturer for further details.

Design considerations:

  • Render carrier boards will be mineral-based, non-gypsum, and dimensionally stable with respect to changes in temperature and relative humidity/ moisture. Boards should be fixed to substrates so that a through-ventilated air space is created.
  • Where required, fire stopping should be provided within cavities at appropriate locations.
  • Water deflection channels should be incorporated into cavities above structural openings unless the cavity is drained/ vented at the opening.
  • Cavities should be provided with insect mesh to prevent infestation. Render carrier board fixings should be countersunk flush with the face of the boards.

Standard product features

Board joints:

PermaRock Joint Masking Tape 060/10: 50 mm wide joint tape with self-adhesive backing, for application across all render board joints to prevent render entry into the joint area.


Movement joints:

Live construction movement joints should be brought through the system. Refer to manufacturer's standard details.

Reinforcement layer:

- Basecoat:

  • PermaRock Bedding Mortar - is a high-performance, polymer-modified, cement-based reinforcement layer render supplied as a mineral dry powder pre-mix, requiring only the addition of water and mixing on site. Used in combination with PermaRock Reinforcing Mesh.

- Mesh reinforcement:

  • PermaRock Reinforcing Mesh: Alkali-resistant coated, multi-strand glass fibre reinforcing mesh for incorporation into a PermaRock basecoat render (PermaRock Bedding Mortar) to create a reinforced basecoat layer which confers mechanical resistance and dimensional stability to the system.

- Mechanical fixings (anchored reinforcement):

Consult manufacturer for recommendations.

Render/ Finish:

- Top (finish) coat:


PermaRock Acrylic K-Finish stippled render/ R-Finish corrugated render:

High performance, ready-to-use, through-colour, synthetic resin textured renders reinforced with siloxane to impart improved water repellence. Flexible, weather resistant, water repellent and water vapour permeable.

  • Texture: Type ‘K’: Stippled; Type ‘R’: Corrugated.
  • Resistance to soiling: Good.
  • Colour fastness: Good; colour shade dependent.
  • Colour range: Over 1250 standard colours (PermaRock Colour Chart; RAL, NCS, BS 4800, etc.). Colour matching available.

PermaRock Brick Slips:

Lightweight, flexible and breathable, synthetic resin brick tiles used to create a brickwork effect.

Facing brick slips and corner (pistol) brick slips provide a traditional or contemporary brick appearance to wall surfaces. Manufactured from high quality raw materials using modern machinery and the skills of experienced craftsmen, these simulated bricks offer a multitude of outstanding product characteristics.

The brick slips offer flexible application and design features, and are durable, robust, impact resistant and easy to clean. The brick slips are bonded to the primed reinforcement layer using a ready-mixed dispersion adhesive. Joints are subsequently pointed with a coloured, semi-dry synthetic pointing mortar.

  • Size: Flat facing bricks: 215 x 65 x 4–6 mm-thick; Corner-facing bricks: 215 x 102 x 65 x 4-6 mm thick. Other sizes available, subject to minimum order quantities.
  • Coverage: Flat facing bricks: Approximately 58 per m²; Corner (pistol) bricks: Approximately 13 per metre.
  • Resistance to soiling: Very good.
  • Colour fastness: Excellent.
  • Colour range: 12 standard colours. Colour matching available, subject to minimum order quantities.
  • Textures: Flat, textured or sand particle.

PermaRock Mineral K-Finish/ R-Finish Through-colour Textured Renders:

Lime-cement-based, non-combustible, lightweight, ecologically-compatible and cost effective renders providing an economical alternative to synthetic through-colour textured renders (due to low consumption rates and ease of application).

Hydraulically curing materials are based on a white cement and lime binder system with lightweight additives, minimal organic content, and additives to induce water repellency.

  • Texture: Type ‘K’: Stippled; Type ‘R’: Corrugated.
  • Resistance to soiling: Good.
  • Colour fastness: Very good.
  • Colour range: Over 900 standard colour shades (lightness factor (LF) ≥30); consult manufacturer's literature for details. For colours with LF 20–30, over-painting with a PermaRock equalising paint is advisable.

PermaRock Silicone ULTRA K-Finish/ R-Finish Through-colour Textured Renders:

Based on a hybrid binder system of organically crosslinked nano-quartz particles and silicone emulsion, offering a self-cleaning effect with enhanced resistance to dirt pick-up and mould/ algae growth, which provides cleaner surfaces for longer than conventional silicone, acrylic or mineral renders.

Lightweight, water repellent, excellent water vapour permeability and can resist aggressive air pollutants. Low environmental impact renders also contain a preservative against coating deterioration due to algae and fungus.

  • Texture: Type ‘K’: Stippled; Type ‘R’: Corrugated.
  • Resistance to soiling: Excellent.
  • Colour range: Over 1000 options, including over 500 ‘A1’ colour shades: PermaRock Colour Chart, RAL (non-A1 shades) and BS 4800 (non-A1 shades). Colour matching service available.
  • Colour fastness: ‘A1’ colours provide excellent resistance to colour fade and chalking. Colour fastness of non-A1 colours is dependent on the colour shade selected.

Beads/ Trims/ Profiles:

Render-only beads, including verge trims, top trims, starter tracks, full system stop beads, render stop beads, window sealing strips (reveals beads), movement joint beads/ profiles for vertical and horizontal joints. Sealing tapes and expansion joint tapes. All as system manufacturer’s or architect’s details, to be supplied by PermaRock.

Additional requirements:

  • Specify movement joint trims, etc. or refer to detail drawings.
  • Specify areas for additional reinforcement mesh e.g. at locations prone to greater risk or intensity of impact, etc.
  • Provide details of brick coursing, bond and features to quoins, door/ window heads and raised feature bands or margins around doors/ windows etc., or refer to drawings.
  • Provide details of colour changes, panelization/ faux joints, etc., or refer to detail drawings.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
25-80-72/150 Multicoat render system
45-55-60/330 Cementitious render

NBS Specification

NBS Buliding logo
This product is associated with the following NBS clauses:

Product specification

An important note about specifying



PermaRock Products Ltd


+44 (0)1509 262924

Product reference

PermaRock Exterior Render System (Back-ventilated Render Rainscreen) (Non-Insulated)

Building height

[ ______ ]


[Brickwork/ blockwork masonry]
[Cross laminated timber (CLT)]
[Insulating concrete framework (ICF)]
[Light steel framing system (SFS)]
[Proprietary render carrier board on supports (forming a through-ventilated air space)]
[Structural insulated panels (SIPs)]
[Timber framing]

Movement joints

[Not required]
Locate as per project drawings.

Reinforcement layer (render carrier)

 - Basecoat:

PermaRock Bedding Mortar - For Silicone ULTRA K-Finish and R-Finish/ Acrylic K-Finish and R-Finish/ Mineral K-Finish and R-Finish/ brick slips.


   Basecoat (sponge float finish):

PermaRock Bedding Mortar - For Silicone ULTRA K-Finish and R-Finish/ Acrylic K-Finish and R-Finish/ Mineral K-Finish and R-Finish/ brick slips.

 - Mesh reinforcement:

PermaRock Reinforcing Mesh

 - Mesh (corner) patches:

PermaRock Reinforcing Mesh - 500 x 250 mm patches incorporated into PermaRend Bedding Mortar at corners of all structural openings and level changes (steps).

 - Corner reinforcement:

PermaRock Corner Reinforcement Angles COR/PL/M

 - Mechanical fixings (anchored reinforcement):
[ ______ ]

Render/ Finish

 - Primer:

PermaRock K&R Primer - For Silicone ULTRA K-Finish and R-Finish/ Acrylic K-Finish and R-Finish/ Brick slips.

 - Top (finish) coat:


[PermaRock Acrylic K-Finish stippled render]
[PermaRock Acrylic R-Finish corrugated render]
[PermaRock Brick Slip Adhesive/ Brick Slips/ Brick Slip Pointing Mortar]
[PermaRock Mineral K-Finish stippled render]
[PermaRock Mineral R-Finish corrugated render]
[PermaRock Silicone ULTRA K-Finish stippled render]
[PermaRock Silicone ULTRA R-Finish corrugated render]

   Grain size:

[Not applicable]
All types other than K or R finishes.
[K 1.5 mm]
For Silicone ULTRA/ Acrylic K-Finishes only.
[K 2.0 mm]
For Silicone ULTRA/ Acrylic/ Mineral K-Finishes only.
[K 3.0 mm]
For Silicone ULTRA/ Acrylic/ Mineral K-Finishes only.
[K 5.0 mm]
For Mineral K-Finishes only.
[R 2.0 mm]
For Silicone ULTRA/ Acrylic R-Finishes only.
[R 3.0 mm]
For Silicone ULTRA/ Acrylic/ Mineral R-Finishes only.
[R 5.0 mm]
For Silicone ULTRA/ Acrylic/ Mineral R-Finishes only.



   Beads/ Trims/ Profiles:


   Equalizing coating/ Paint:

[PermaRock Silicone ULTRA Facade Coating]
Self-cleaning facade paint with nano-quartz matrix structure. For use with K-Finish/ R-Finish renders with lightness factor < 20.


[ ______ ]

Additional requirements

[As drawing]
See 'Options' below and insert requirements.

Manufacturer details

Jubilee Drive,
Leicestershire, LE11 5TW
Tel +44 (0)1509 262924
Fax +44 (0)1509 230063
NBS Plus
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